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<pre class="textdiagram" id="fig38">
+--------+  +--------+  +--------+
| Client |  | Client |  | Client |
+--------+  +--------+  +--------+
|  REQ   |  |  REQ   |  |  REQ   |
+---+----+  +---+----+  +---+----+
    |           |           |
    +-----------+-----------+
                |
            +---+----+
            | ROUTER |  Frontend
            +--------+
            | Device |  LRU queue
            +--------+
            | ROUTER |  Backend
            +---+----+
                |
    +-----------+-----------+
    |           |           |
+---+----+  +---+----+  +---+----+
|  REQ   |  |  REQ   |  |  REQ   |
+--------+  +--------+  +--------+
| Worker |  | Worker |  | Worker |
+--------+  +--------+  +--------+
</pre>
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